Hairpin Type Stator Coil Forming Apparatus and Forming Method

ABSTRACT

In an embodiment a method includes cutting a material coil by a predetermined length, forming a vertex and inclined portions on the material coil, loading the vertex and the inclined portion so as to be interposed between an upper mold and a lower mold, forming the vertex into a front/rear bent portion so that the inclined portions are positioned on different lines based on the vertex by combining the upper and lower molds, loading ends of the inclined portions so as to be interposed between clamping pins and rotating a clamping part so that the inclined portions are rounded in front and rear directions.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a divisional application of U.S. application no. 16/896,023,entitled “Hairpin Type Stator Coil Forming Apparatus and FormingMethod,” which was filed on Jun. 8, 2020, which claims priority toKorean Patent Application No. 10-2019-0123902, filed in the KoreanIntellectual Property Office on Oct. 7, 2019, each of which is herebyincorporated herein by reference.

TECHNICAL FIELD

The present invention relates to a hairpin type stator coil formingapparatus and a forming method thereof.

BACKGROUND

Generally, a hybrid vehicle or an electric vehicle called anenvironmentally-friendly vehicle may generate driving force by anelectric motor (hereinafter referred to as a “driving motor”) thatobtains rotational power from electrical energy.

The hybrid vehicle may be driven in an electric vehicle (EV) mode, whichis a pure electric vehicle mode that uses only the power of the drivingmotor, or in a hybrid electric vehicle (HEV) mode, which uses rotationalpower of both an engine and the driving motor as a power source.

In addition, a general electric vehicle travels using the rotationalforce of the driving motor as a power source.

For example, most of the driving motors used as the power source of theenvironmentally-friendly vehicle are permanent magnet synchronous motors(PMSMs).

As such, the driving motor as a permanent magnet synchronous motor usedas a power source for an environmentally-friendly vehicle basicallyincludes a stator generating a magnetic flux, a rotor that is spacedapart from the stator by a predetermined gap and performs rotationalmovement, and a permanent magnet installed at the rotor.

Here, the stator is provided with a plurality of slots formed at aninner circumferential side of a stator core, and a stator coil is woundin each slot.

When an alternating current is applied to the stator coil, a rotatingmagnetic field is generated in the stator, and rotation torque may begenerated in the rotor by the rotating magnetic field.

The driving motor may be classified into a distributed winding type ofdriving motor and a centralized winding type of driving motor accordingto a winding method of the stator coil, and a stator of the distributedwinding type of driving motor may be classified into a segment coilstator and a distributed winding coil stator according to a coil windingmethod.

In this case, the segment coil stator is a stator made by a method inwhich a coil is previously formed in a predetermined shape and theninserted into a slot of the stator core, and the distributed windingcoil stator is a stator made by a method of inserting a bundle of coilsinto the slot of the stator core.

Meanwhile, an output of the driving motor is known to be proportional tothe number of turns of the coil wound on the stator core.

However, when the number of turns of the coil is increased, a size ofthe stator core or driving motor inevitably increases, which makes itdifficult to downsize the driving motor.

Therefore, a method of increasing a stacking factor of the coil wound onthe stator core may be considered in order to improve the output of thedriving motor without increasing the size of the driving motor.

In other words, a method of increasing the stacking factor of the coilby minimizing a dead space between the stator core and the winding coilor a dead space between respective coils may be considered.

In the above aspect, in place of using a ring-shaped coil (referred toas “ring-shaped wire” in the art) having a circular section as a coilwinding, a method of using a flat coil (referred to as “flat wire” inthe art) having a square section has been actively studied.

The flat coil may reduce the dead space and improve the stacking factordue to a shape of a section thereof as compared with the ring-shapedcoil.

However, the flat coil has a difficulty in coil winding work as comparedwith the ring-shaped coil.

This is because the flat coil is manufactured to have a widecross-section as compared with the ring shaped coil in order to maximizethe stacking factor so it is difficult to use a winding machine.

Accordingly, as a method of easily performing coil winding work of theflat coil in the segment stator of the distributed winding drivingmotor, a method in which a plurality of separate hairpin type(substantially U or V shape) of stator coils (also referred to as“conductors” in the art) are inserted into each slot of the stator core,and in which the stator coil adjacent to a radial direction in the slotis welded such that the coil winding of the stator core is continuouslyformed, has been proposed.

The driving motor having the stator of the hairpin winding typemanufactured by the method mentioned above is also referred to as a“hairpin driving motor” in the art.

According to the structure of the stator coil winding of theabove-described hairpin driving motor, it is possible to overcomelimitations caused by a winding machine, and to relatively easilyperform winding work even in the case of the square coil, and further,it is possible to implement a miniaturized motor with high power byincreasing the stacking factor of the coil.

On the other hand, a process of forming the stator coil of the hairpintype as described above to have a predetermined shape may besubstantially classified into a computer numerical control (CNC) formingmethod and a press forming method, and since there are several types ofhairpins in one hairpin driving motor, the CNC forming method that maybe applied to multiple models is advantageous.

However, according to the CNC forming method that may be applied tovarious models, a production speed of one hairpin is about 6 seconds,which is somewhat slow; while according to the press forming method of afast speed, a production speed of one hairpin is about 3 seconds, whichis a speed providing twice the productivity of the CNC forming method,but the press forming method may produce only a single model.

Therefore, research and development on a method for forming the hairpinis necessary.

The above information disclosed in this Background section is only forenhancement of understanding of the background of the invention, andtherefore it may contain information that does not form the prior artthat is already known to a person of ordinary skill in the art.

SUMMARY

The present invention relates to a hairpin type stator coil formingapparatus and a forming method thereof. Particular embodiments relate toa hairpin type stator coil forming apparatus and a forming method thatmay form a stator coil corresponding to multiple models.

Embodiments of the present invention provide a hairpin type of statorcoil forming apparatus and forming method that may produce various typesof stator coils.

An embodiment of the present invention provides a hairpin type of statorcoil forming apparatus, including a first forming machine that forms avertex so that a central portion of a material coil protrudes upward,and forms inclined portions inclined to both sides of the vertex, asecond forming machine in which the material coil bent-formed by thefirst forming machine is loaded, and that forms a front/rear bentportion by bending one side inclined portion and a portion of the otherside inclined portion based on the vertex, and a third forming machinein which the material coil bent-formed by the second forming machine isloaded, and that roundly forms the inclined portion in front and reardirections.

The first forming machine may include a lower central die configured tobe provided with: a forming surface having a triangular cross-section,lower left and right dies configured to be slide-movable in left andright directions at both sides connected to the forming surface of thelower central die, and to adjust a length of the inclined portion of thematerial coil, a moving bracket configured to be supported through aframe at an upper portion of the lower central die, and to be movableupward and downward from an upper portion of the frame, upper springparts configured to be disposed to be spaced apart from each other by apredetermined distance at both sides with respect to a center of theforming surface of the lower central die through the moving bracket, andto press-fit the material coil toward the lower central die so that avertex and an inclined portion are formed on the material coil throughthe forming surface when the moving bracket moves downward, and upperroller parts configured to be disposed at both outer sides of the upperspring part through the moving bracket, and to adjust a length of theinclined portion by press-fitting the material coil based on the lowerleft and right dies.

The lower central die may include an upper portion provided with aforming surface for forming the inclined portion and the vertex on thematerial coil, and both sides formed with mounting grooves on which thelower left and right dies are mounted.

The lower left and right dies may be mounted to be slidably moved inleft and right directions by operations of motors in the mountinggrooves.

The moving bracket may be mounted on a screw rotated by the motorinstalled in the frame to be movable in up and down directions, and itsmoving position is limited by a stopper disposed in a lower end portionof the screw.

The upper spring part may include a spring mounted in a catching holeformed on the moving bracket, a spring rod disposed inside the spring tobe installed through an upper portion of the frame, and a spring blockthat is connected to an end of the spring rod and press-fits thematerial coil toward the lower central die as the moving bracket movesdownward.

The upper roller part may include a supporting rod mounted on the movingbracket, and a roller that is rotatably mounted on a front end of thesupporting rod to bend and press-fit the material coil toward the lowerleft and right dies as the moving bracket moves downward.

The first forming machine may further include a cutting part that cutsthe material coil by a set length in a rear direction in which thematerial coil is supplied, wherein the cutting part may include acutting die disposed under the material coil, and a cutter disposed atan upper side corresponding to the cutting die to be driven in up anddown directions.

The second forming machine may include upper and lower molds in whichthe vertex and the inclined portion of the material coil formed by thefirst forming machine are interposed, and step surfaces that form thefront/rear bent portion by forming the vertex so that one side inclinedportion and the other side inclined portion are positioned on differentlines based on the vertex of the material coil, and may be formed onopposite inner surfaces of the upper and lower molds, respectively.

The third machine may include clamping parts respectively disposedcorresponding to both ends of the inclined portion of the material coilformed by the second forming machine so that the inclined portion isclamped through clamping pins.

The clamping part may include a first clamping part that is movableforward and backward based on a center of the rack gear by a guiderwhile clamping one side of the inclined portion, and a second clampingpart that is mounted to rotate with the rack gear rotating by a piniongear and rotates in one direction with respect to the fixed firstclamping part while clamping the other side of the inclined portion.

The clamping part may be configured so that the material coil rotates ina clamped state by the clamping pin to adjust a round angle of theinclined surface.

Another embodiment of the present invention provides a hairpin type ofstator coil forming method that forms a hairpin type stator coilincluding a front/rear bent portion formed at a vertex by bending andforming a material coil, inclined portions that are inclined downwardfrom the front/rear bent portion to both sides and are rounded in frontand rear directions, and leg portions connected downwardly to theinclined portions, by using a hairpin type stator coil formingapparatus, the method including a first step of cutting the materialcoil by a first forming machine by a predetermined length and forming avertex and an inclined portion on the material coil, a second step ofloading the vertex and the inclined portion so as to be interposedbetween an upper mold and a lower mold, and forming the vertexfront/rear bent portion so that one inclined portion and the otherinclined portion are positioned on different lines based on the vertexby combining the upper and lower molds, and a third step of loading bothends of the inclined portion so as to be interposed between clampingpins and rotating a clamping part to form the inclined portion roundedforward and backward.

The first step may include entering the material coil into an upperportion of a lower central die, cutting the material coil by a cuttingpart disposed at a rear side of an entry direction of the material coil,forming a vertex and an inclined portion on the material coil along aforming surface by moving a moving bracket downward such that a springpart press-fits the material coil to the forming surface of the lowercentral die, and continuously moving the moving bracket downward, sothat an upper roller part press-fits the material coil along lower leftand right dies.

The first step may further include moving the lower left and right diesin left and right directions to be loaded at a predetermined positionwhen the upper roller part moves downward to press-fit the material coiltoward the lower left and right dies.

The second step may include, loading the material coil so that thevertex and the inclined portion are interposed between upper and lowermolds, after the first step, and forming the vertex into a front/rearbent portion so that one inclined portion and the other inclined portionare positioned on different lines based on the vertex by combining theupper and lower molds.

The third step may include loading the material coil so that both endsof the inclined portion are interposed between clamping pins, after thesecond step, and forming the inclined portion of the material coil to berounded forward and backward by rotating the second clamping part in onedirection with respect to a first clamping part in a state in which thematerial coil is clamped by the clamping pins.

The first clamping part may be driven along a guider in a directioncloser to or further away from the second clamping part.

In the third step, an amount of the inclined portion being bent in frontand rear directions may be determined according to an angle at which thefirst clamping part rotates.

The hairpin type of stator coil forming apparatus and forming methodaccording to the embodiments of the present invention may change onlyset values inputted to a first forming machine, a second formingmachine, and a third forming machine to set lengths of inclined portionsof a material coil, an angle of a vertex between the inclined portions,a bent degree of the inclined portion, and the like. Therefore, it isapplicable to the production of various types of stator coils, and it ispossible to cope with multiple models with one piece of equipment, andto improve productivity.

Further, effects that may be obtained or expected from embodiments ofthe present invention are directly or suggestively described in thefollowing detailed description. That is, various effects expected fromembodiments of the present invention will be described in the followingdetailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a schematic view of a structure of a hairpin typestator of a driving motor applied to an embodiment of the presentinvention.

FIG. 2 illustrates a schematic view of a hairpin type of stator coilforming apparatus according to an embodiment of the present invention.

FIG. 3 illustrates a schematic view of a first forming machine appliedto a hairpin type of stator coil forming apparatus according to anembodiment of the present invention.

FIG. 4 and FIG. 5 illustrate schematic views of a second forming machineapplied to a hairpin type of stator coil forming apparatus according toan embodiment of the present invention.

FIG. 6 illustrates a schematic view of a third forming machine appliedto a hairpin type of stator coil forming apparatus according to anembodiment of the present invention.

FIG. 7 to FIG. 15 illustrate schematic views of a forming method forforming a stator coil by using a hairpin type of stator coil formingapparatus according to an embodiment of the present invention.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

The present invention will be described more fully hereinafter withreference to the accompanying drawings, in which embodiments of theinvention are shown. As those skilled in the art would realize, thedescribed embodiments may be modified in various different ways, allwithout departing from the spirit or scope of the present invention.

To clearly describe the embodiments of the present disclosure, portionswhich do not relate to the description are omitted, and like referencenumerals designate like elements throughout the specification.

Further, in the following detailed description, terms of elements, whichare in the same relationship, are divided into “first”, “ second”, etc.,but the embodiments of the present invention are not necessarily limitedto the order in the following description.

FIG. 1 illustrates a schematic view of a structure of a hairpin typestator of a driving motor applied to an embodiment of the presentinvention.

Referring to FIG. 1 , a hairpin type of stator of a driving motorapplied to an embodiment of the present invention may be applied to adriving motor for a hybrid vehicle and/or an electric vehicle, asenvironmentally-friendly vehicles that obtain driving force fromelectrical energy.

For example, the driving motor may be applied to a permanent magnetsynchronous motor (PMSM).

In the embodiments of the present invention, the driving motor includesa stator 1, a rotor (not shown) spaced apart from the stator 1 by apredetermined gap, and a plurality of permanent magnets (not shown)installed on the rotor.

The stator 1 includes a stator core 3 in which a plurality of electricalsteel sheets are stacked, and a hairpin type of stator coil 7 (generallyreferred to as a “conductor” in the art) is wound on the stator core 3through a plurality of slots 5.

In addition, the rotor includes a rotor core in which a plurality ofelectrical steel sheets are stacked in an axial direction.

The permanent magnet mentioned above is inserted into and installed ininsertion holes provided in the rotor core.

Here, the driving motor may be applied to an inner-type synchronousmotor having a rotor disposed inside the stator 1, or may be applied toan outer-type synchronous motor having a rotor disposed outside thestator 1.

The hairpin type of stator coils 7 described above are flat wire coils,and for example, the hairpin type of stator coil 7 includes a front/rearbent portion 17 formed in a central portion thereof, inclined portions11 formed downward at both sides based on the front/rear bent portion17,and leg portions 15 formed vertically below respective inclinedportions 11, its overall shape is a hairpin shape in which a U shape orV shape is disposed upside down, and it is a flat coil with aquadrangular cross-section.

In this case, in the stator coil 7,one inclined portion is disposed toprotrude forward or backward compared to the other inclined portionbased on the front/rear bent portion 17,and an overall shape of theinclined portion 11 may be rounded forward or backward.

The hairpin type of stator coils 7 are inserted into a set layer(indicated by a dashed-dotted line in the drawing) of the slot 5,and endportions of a pair of leg portions 15 protrude to are outside of theslot 5, and while the protruding portions are welded, they may form anelectrically connected coil winding.

As described above, although an embodiment of the present invention inwhich the hairpin type of winding is the stator in the driving motorapplied to the environmentally friendly vehicle has been described, thescope of the present invention is not limited thereto, and a technicalscope of the present invention is applicable to any driving motorprovided with various kinds and purposes of hairpin-type stators.

FIG. 2 illustrates a schematic view of a hairpin type of stator coilforming apparatus according to an embodiment of the present invention.

A hairpin type of stator coil forming apparatus according to anembodiment of the present invention basically includes a first formingmachine 100, a second forming machine 200,and a third forming machine300, which will be described for each configuration.

Regarding the hairpin type stator coil 7 according to an embodiment ofthe present invention, a straight type of material coil 10 is suppliedto the first forming machine 100 to be bent in the first forming machine100 to form the inclined portion 11, a vertex 13, and the leg portions15. The material coil 10 formed in the first forming machine 100 istransferred to the second forming machine 200 through a transferringgripper to form the front/rear bent portion 17,and the material coil 10formed in the second forming machine 200 is transferred to the thirdforming machine 300 through a transferring gripper to round the inclinedportion 11, so the hairpin type stator coil 7 is finally completed.

FIG. 3 illustrates a schematic view of a first forming machine appliedto a hairpin type of stator coil forming apparatus according to anembodiment of the present invention.

In the present specification, based on FIG. 3 , an entry direction ofthe material coil 10 described below is set to the left and rightdirections as a reference direction, and a portion directed upward isdefined as an upper portion, an upper end, an upper surface, and anupper end portion, and a portion directed downward is defined as a lowerportion, a lower end, a lower surface, and a lower end portion.

In addition, hereinafter, an “end (one side end or the other end)” maybe defined as any one end, or may be defined as a predetermined portion(one end portion or the other end portion) including the end.

Referring to FIG. 3 , the first forming machine 100 is supplied with thestraight material coil 10 from a stator coil supplying apparatus (notshown).

Briefly explaining the stator coil supplying apparatus, it unwinds theflat material coil 10 wound on a coil unwinder, flattens the materialcoil 10 through a coil straightener, and then supplies the flattenedmaterial coil 10 to the first forming machine 100 according to anembodiment of the present invention.

As described above, the first forming machine 100 supplied with thematerial coil 10 from the stator coil supplying apparatus bends andforms the material coil 10 so that a center portion of the material coil10 protrudes to one side and forms a vertex 13 while forming theinclined portion 11.

The first forming machine 100 includes a lower central die 110, lowerleft and right dies 120, a moving bracket 130, an upper spring part 140,an upper roller part 150, and a cutting part 160.

The lower central die 110 is disposed corresponding to a lower center ofthe material coil 10.

The lower central die 110 has a forming surface 111 of which avertically directional cross-section is a triangular cross-section.

In the lower central die 110, the forming surface 111 has apredetermined width in front and rear directions so that the materialcoil 10 may be seated.

The forming surface 111 is fixed to the frame F at a position excludinga portion on which the material coil 10 is seated.

The lower central die 110 is configured to form the inclined portion 11and the vertex 13 in the material coil 10 through the forming surface111.

In addition, the lower central die 110 may be provided to be movable inup and down directions through a first motor M1 disposed at a lower sidethereof.

Mounting grooves 113 are formed in both sides of the lower central die110, and the lower left and right dies 120 are mounted on the mountinggrooves 113 so as to be able to slide in left and right directions.

The mounting grooves 113 may be formed in both sides of the lowercentral die 110 connected to the forming surface 111.

The lower left and right dies 120 may be mounted to be able to slide inthe left and right directions by an operation of a second motor M2 inthe mounting groove 113.

The lower left and right dies 120 may be guided by a separate member(not shown) that may slide and move in the mounting groove 113,forexample, a roller member.

The lower left and right dies 120 may be connected to the formingsurface 111 to adjust a length of the inclined portion 11 of thematerial coil 10 according to its movement.

For example, when the lower left and right dies 120 are moved towardrespective outsides, the length of the inclined portion 11 may be formedlong.

In addition, the moving bracket 130 may be disposed above the lowercentral die 110 and the lower left and right dies 120.

The moving bracket 130 may be supported through the frame F fixed to theground.

The moving bracket 130 is installed on a screw 131 vertically disposedfrom an upper portion of the frame F to be vertically movable along thescrew 131.

The moving bracket 130 is vertically movably mounted on the screw 131rotated by a third motor M3 installed on the upper portion of the frameF, and its moving position may be limited by a stopper 133 disposed at alower end portion of the screw 131.

The upper spring part 140 and the upper roller part 150 are mounted onthe moving bracket 130.

The upper spring part 140 is mounted on two positions spaced apart fromeach other by a predetermined interval based on the center of theforming surface 111 of the lower central die 110 through the movingbracket 130.

The upper spring part 140 includes a catching end 141,a spring 143,aspring block 145,and a spring rod 147.

The catching end 141 is fitted through a catching hole 135 formed in themoving bracket 130 to fix the upper spring part 140.

The spring 143 may be connected to the catching end 141,and may be madeof a material having relatively strong elasticity.

In addition, a spring rod 147 is disposed inside the spring 143,and thespring rod 147 may penetrate the moving bracket 130 to be mounted on theupper portion of the frame F.

The spring rod 147 may limit a position of the spring 143,and the springblock 145 is connected to an end portion of the spring rod 147.

The spring block 145 is a portion that directly contacts the materialcoil 10, and when it is press-fitted in contact with a surface of thematerial coil 10, it is preferable that it is made of a material thatdoes not cause scratches or the like on the surface of the material coil10.

The upper spring part 140 may press-fit the material coil 10 toward thelower central die 110 as the moving bracket 130 moves downward.

The upper spring part 140 may press-fit the material coil 10 toward thelower central die 110 so that the inclined portion 11 and the vertex 13are formed on the material coil 10 along the forming surface 111 of thelower central die 110.

The moving bracket 130 is installed with upper roller parts 150, whereinthe upper roller parts 150 are respectively disposed at both outer sidesof the upper spring part 140.

The upper roller parts 150 can press-fit the material coil 10 togetherwith the lower left and right dies 120 to adjust the length of theinclined portion 11 of the material coil 10.

In addition, the upper roller parts 150 may operate in a directioncloser to or farther from each other through fourth motors M4 installedat both end portions of the moving bracket 130.

The upper roller part 150 includes a supporting rod 151 and a roller153.

The supporting rod 151 is installed on the moving bracket 130,and aroller 153 is rotatably connected to a front end of the supporting rod151.

In this case, the roller 153 may be rotatably mounted at the front endof the supporting rod 151 to be in rolling contact with the materialcoil 10 to operate with the material coil 10 interposed between thelower left and right dies 120, and determines a length of the inclinedportion 11 on the material coil 10, so that the leg portion 15 connectedto the inclined portion 11 may be formed.

Finally, the first forming machine 100 includes the cutting part 160.

The cutting part 160 may be installed at a rear side of a direction inwhich the material coil 10 is supplied to the first forming machine 100.

The cutting part 160 includes a cutting die 161 and a cutter 163.

The cutter 163 is mounted to be vertically driven at an upper sidecorresponding to the cutting die 161.

The cutter 163 may be mounted to be vertically driven by an operation ofa fifth motor M5 or cylinder.

When the material coil 10 is supplied to the first forming machine 100by a predetermined length, the cutting part 160 may move the cutter 163downward to cut the material coil 10.

In this case, the cutter 163 is installed to cut the material coil 10corresponding to a front end of the cutting die 161.

The cutting part 160 may move in a direction closer to or farther fromthe frame F.

That is, the cutting part is configured to move through a fixed block B,and may be moved through a sixth motor M6 connected to the fixed blockB.

FIG. 4 and FIG. 5 illustrate schematic views of a second forming machineapplied to a hairpin type of stator coil forming apparatus according toan embodiment of the present invention.

Referring to FIG. 4 , the second forming machine 200 includes an uppermold 210 and a lower mold 220,and it may be configured in pluralaccording to a shape of a stepped surface 230 formed on an inner surfaceof each of the upper mold 210 and the lower mold 220.

For example, the shape of the front/rear bent portion 17 variesaccording to the shape of the stepped surface 230 of the second formingmachine 200, and correspondingly, upper molds (210 a, 210 b, 210 c, 210d, ...) and lower molds (220 a, 220 b, 220 c, 220 d, ...) havingdifferent shapes may be disposed in plural, thus a forming process ispossible if necessary.

Referring to FIG. 5 , the material coil 10 loaded in the second formingmachine may be loaded with the inclined portion 11 and the vertex 13lying horizontally so that they face forward.

The stepped surface 230 is formed on each of inner surfaces of the uppermold 210 and the lower mold 220 facing each other.

The second forming machine 200 is configured so that the vertex 13 ofthe material coil 10 corresponds to the stepped surface 230 of each ofthe upper mold 210 and the lower mold 220.

The second forming machine 200 is for forming the material coil 10 sothat one inclined portion and the other inclined portion 11 arepositioned on different lines based on the vertex 13 of the materialcoil 10.That is, the second forming machine 200 is an apparatus forforming the bent portion 17 by bending and forming portions of the oneinclined portion and the other inclined portion 11.

That is, the second forming machine 200 may bend and form the vertex 13through the stepped surface 230 to form the front and rear bent portion17,and may form them so that the one inclined portion is positionedforward or rearward compared to the other inclined portion (see thedirection of FIG. 3 ).

FIG. 6 illustrates a schematic view of a third forming machine appliedto a hairpin type stator coil forming apparatus according to anembodiment of the present invention.

Referring to FIG. 6 , the material coil 10 may be loaded on the thirdforming machine 300 in a state in which the inclined portion 11 and thefront/rear bent portion 17 are vertically upright.

In the present embodiment, the third forming machine 300 and the loadedmaterial coil 10 are shown in a direction viewed from the top to helpunderstanding of the embodiments of the invention.

The third forming machine 300 includes first and second clamping parts310 a and 310 b, and both ends of the inclined portion 11 of thematerial coil 10 transferred from the transferring gripper are loaded tobe interposed in the clamping pins 311 of respective clamping parts 310.

The clamping pins 311 may clamp the material coil 10 in the front andrear directions (see FIG. 1 ).

The clamping pins 311 are movable in a direction away from or towardseach other by a cylinder operation.

The clamping part 310 includes the first clamping part 310 a and thesecond clamping part 310 b rotating together with a rack gear 317rotated by a pinion gear 315.

The first clamping part 310 a is configured to move forward or backwardbased on a center of the rack gear 317 by a guider 313 while clampingone side of the inclined portion 11.

The second clamping part 310 b is configured to rotate with the rackgear 317 at the other side of the rack gear 317.

The second clamping part 310 b is configured to rotate in one directionwith respect to the fixed first clamping part 310 a while clamping theother side of the inclined portion 11.

That is, the clamping part 310 may form the inclined portions 11 to berounded by rotating while clamping respective ends of both inclinedportions 11 of the material coil 10 through the clamping pins 311.

That is, the material coil 10 may be formed so that the inclined portion11 may be rounded in the front and rear directions through the thirdforming machine 300.

Here, the clamping part 310 may set the amount of bend in the front andrear directions of the inclined portion 11 according to a rotating angleof the second clamping part 310 b.

In other words, the greater the rotating angle at which the secondclamping part 310 b rotates with respect to the first clamping part 310a, the greater the degree in which the inclined portion 11 of thematerial coil 10 is bent in the front and rear directions.

Here, the transferring gripper may wait while clamping the material coil10 until the forming process is completed in the third forming machine300.

FIG. 7 to FIG. 15 sequentially illustrate schematic views of a formingmethod for forming a stator coil by using a hairpin type of stator coilforming apparatus according to an embodiment of the present invention.

The method for forming the stator coil 7 by using the first formingmachine 100 as described above is as follows.

Referring to FIG. 3 , the material coil 10 is supplied to the firstforming machine 100 by a predetermined length in a state in which thematerial coil 10 is supported by the lower central die 110.

Subsequently, referring to FIG. 7 , the moving bracket 130 movesdownward along the screw 131 by the operation of the third motor M3, andthe upper spring part 140 press-fits the material coil to the formingsurface 111 of the lower central die 110.

At the same time, the cutter 163 of the cutting part 160 is moveddownward by the operation of the fifth motor M5 to cut the material coil10.The material coil 10 may be fixed by the elastic force of the spring143.

In this case, as the upper spring part 140 press-fits the material coil10, the inclined portion 11 and the vertex 13 are formed on the materialcoil 10 along the forming surface 111 of the lower central die 110.

Referring to FIG. 8 , the moving bracket 130 is continuously moveddownward, so that the upper roller part 150 forms the leg portion 15connected to the inclined portion 11 on the material coil 10 whilepress-fitting the material coil 10 based on the lower left and rightdies 120.

Here, the lower left and right dies 120 are moved in the left and rightdirections to be loaded at a set position.

That is, the lower left and right dies 120 move in the left and rightdirections in the mounting grooves 113 of the lower central die 110 toadjust the length of the inclined portion 11 of the material coil 10.

Referring to FIG. 9 , the inclined portion 11, the vertex 13, and theleg portions 15 are bent and formed on the material coil 10 by the firstforming machine 100 as described above, and the material coil 10 istransferred to the second forming machine 200 through a transferringgripper (not shown).

Referring to FIG. 4 , the material coil 10 is loaded so that theinclined portion 11 and the vertex 13 of the material coil 10 correspondbetween the upper mold 210 and the lower mold 220 of the second formingmachine 200, and more specifically, so that the vertex 13 corresponds torespective step surfaces 230 of the upper mold 210 and the lower mold220.

Referring to FIG. 10 , the upper mold 210 and the lower mold 220 arecombined to bend the vertex 13 of the material coil 10 through thestepped surface 230.

That is, the front/rear bent portion 17 is formed by bending the vertex13 so that one of the one inclined portion 11 and the other inclinedportion 11 is positioned forward or rearward so that the one inclinedportion and the other inclined portion are positioned on differentlines, based on the vertex 13 of the material coil 10.

In this case, the transferring gripper may wait while clamping thematerial coil 10 until the forming process is completed in the secondforming machine 200.

Referring to FIG. 11 , next, the upper mold 210 and the lower mold 220are separated.

The upper mold 210 and the lower mold 220 may be manufactured in a smallsize corresponding to the size of the material coil 10, and may beconfigured to be automatically replaceable whenever necessary byincluding various types of upper molds 210 and lower molds 220.

Referring to FIG. 12 , the front/rear bent portion 17 is formed on thematerial coil 10 by the second forming machine 200 as described above,and then, the material coil 10 is transferred to the third formingmachine 300 through a transferring gripper (not shown).

Referring to FIG. 5 , the material coil 10 is loaded so that thefront/rear bent portion 17 of the material coil 10 corresponds betweenthe clamping pins 311 of the third machine 300.

Referring to FIG. 13 , the clamping pins 311 move in a direction towardseach other to clamp each end of the inclined portion 11 of the materialcoil 10.

Referring to FIG. 14 , as the second clamping part 310 b rotates withthe rack gear 317, a relative angle between the second clamping part 310b and the first clamping part 310 a is changed.

Accordingly, the inclined portion 11 is rounded in the front and reardirections.

Referring to FIG. 15 , the inclined portion 11 of the material coil 10is roundly formed in the front and rear directions by the third formingmachine 300 as described above to finally complete the stator coil 7.

Since the hairpin type of stator coil forming apparatus and formingmethod according to the embodiments of the present invention may set thelength of the inclined portion 11, the angle of the vertex 13 betweenthe inclined portions 11, the bent degree of the inclined portion 11,and the like by the first forming machine 100, the second formingmachine 200, and the third forming machine 300, the stator coils havingvarious shapes may be formed.

For example, the length of the inclined portion 11 and the angle of thevertex 13 may be adjusted by adjusting the positions of the lower leftand right dies 120 of the first forming machine 100 in the left andright directions, it is possible to adjust the bent degree of thefront/rear bent portion 17 by changing the design of the step surfaces230 of the upper mold 210 and the lower mold 220 of the second formingmachine 200, and the bent degree of the inclined portion 11 may be setby adjusting the rotating angle of the clamping part 310 of the thirdforming machine 300.

In addition, since the hairpin type of stator coil forming apparatus andforming method according to the embodiments of the present invention maychange the shape of the manufactured stator coil by changing only theset values inputted to the first forming machine 100, the second formingmachine 200, and the third forming machine 300, it is possible toimprove productivity.

While this invention has been described in connection with what ispresently considered to be practical embodiments, it is to be understoodthat the invention is not limited to the disclosed embodiments, but, onthe contrary, is intended to cover various modifications and equivalentarrangements included within the spirit and scope of the appendedclaims.

What is claimed is:
 1. A method for forming a hairpin type of stator coil, the method comprising: cutting a material coil by a predetermined length; forming a vertex and inclined portions on the material coil; loading the vertex and the inclined portion so as to be interposed between an upper mold and a lower mold; forming the vertex into a front/rear bent portion so that the inclined portions are positioned on different lines based on the vertex by combining the upper and lower molds; loading ends of the inclined portions so as to be interposed between clamping pins; and rotating a clamping part so that the inclined portions are rounded in front and rear directions.
 2. The method of claim 1, wherein cutting the material coil and forming the vertex and the inclined portions comprise: entering the material coil into an upper portion of a lower central die; cutting the material coil using a cutting part disposed at a rear side of an entry direction of the material coil; forming the vertex and the inclined portions on the material coil along a forming surface by moving a moving bracket downward such that a spring part press-fits the material coil to the forming surface of the lower central die; and continuously moving the moving bracket downward so that an upper roller part press-fits the material coil along lower left and right dies.
 3. The method of claim 2, wherein forming the vertex and the inclined portions comprises moving the lower left and right dies in left and right directions to be_([MK1]) loaded at a predetermined position when the upper roller part moves downward to press-fit the material coil toward the lower left and right dies.
 4. The method of claim 1, wherein loading the vertex and the inclined portion comprises loading the material coil so that the vertex and the inclined portions are interposed between upper and lower molds, and wherein forming the vertex into the front/rear bent portions comprises forming the vertex into the front/rear bent portion so that the inclined portions are positioned on different lines based on the vertex by combining the upper and lower molds.
 5. The method of claim 1, wherein loading ends of the inclined portions comprises loading the material coil so that the ends of the inclined portions are interposed between the clamping pins, wherein the clamping part includes a first clamping part and a second clamping part, and wherein rotating the clamping part comprises forming the inclined portions of the material coil to be rounded forward and backward by rotating the second clamping part in one direction with respect to the first clamping part in a state in which the material coil is clamped by the clamping pins.
 6. The method of claim 5, wherein the first clamping part is driven along a guider in a direction closer to or further away from the second clamping part.
 7. The method of claim 5, wherein an amount of the inclined portions being bent in the front and rear directions is determined according to an angle at which the first clamping part rotates. 